TITLE: Linear hydroquinone phenoxy polymers and process
United States Patent 4383101
ABSTRACT:
This invention relates to a process for the preparation of
thermoplastic polymers. Specifically it relates to a process for the
preparation of a substantially linear, high molecular weight phenoxy
resin from substituted hydroquinone, less than 80 mole percent of
hydroquinone and optionally up to about 20 mole percent of a second
aromatic diol, epichlorohydrin (or another epihalohydrin) and a base,
such as sodium hydroxide.
Hydroquinone phenoxy resins of this invention are characterized by low
permeability to oxygen and carbon dioxide and are, therefore, useful as
a gas-barrier layer in multilayer plastic film constructions used in
food packaging and beverage bottle applications, for example. For use
in such applications, the resin is generally in the form of a thin,
uniform film prepared by extrusion, casting, or other such method. It
is highly desirable that polymers used in this manner be as free as
possible from chain branches or cross-links, as these lead to the
formation of gel particles which cause imperfections in the polymer
film. These imperfections, in turn, detract from the appearance of the
film. Moreover, as is well known, increasing the amount of chain
branching in a polymer results in an undesirable reduction of
flexibility and toughness.
INVENTORS:
Olsen, Eric G. (Kingsport, TN)
Jackson Jr., Winston J. (Kingsport, TN)
APPLICATION NUMBER: 06/237174
PUBLICATION DATE: 05/10/1983
FILING DATE: 02/23/1981
ASSIGNEE: Eastman Kodak Company (Rochester, NY)
PRIMARY CLASS: 528/93
OTHER CLASSES: 428/413, 528/87, 528/95, 528/104
INTERNATIONAL CLASSES: C08G65/26; (IPC1-7): C08G59/06
FIELD OF SEARCH: 528/87, 528/93, 528/95, 528/104
US PATENT REFERENCES:
4267301 Linear hydroquinone phenoxy polymers and process May, 1981
Olsen et al. 528/87
3767618 N/A October, 1973 Harriston et al. 528/95
3701680 N/A October, 1972 Lee et al. 117/138.8F
3395118 Modified thermoplastic polyhydroxyethers July, 1968 Reinking et
al. 528/93
3238087 Method of making laminated structural elements and article
produced thereby March, 1966 Norwalk et al. 161/185
2602075 Production of thermoplastic resins and the production from such
resins of threads, fibres, filaments, and the like July, 1952 Carpenter
et al. 528/93
PRIMARY EXAMINER: Lee, Lester L.
Attorney, Agent or Firm:
Heath Jr., William P.
Reece III, Daniel B.
Parent Case Data:
This application is a continuation-in-part of our application Ser. No.
108,722 filed Dec. 31, 1979 now U.S. Pat. No. 4,267,301.
CLAIMS:
We claim:
1. Process for the preparation of high molecular weight hydroquinone
phenoxy polymer from at least 21 mole percent hydroquinone substituted
with one or two substituents selected from chlorine or an alkyl group
containing 1-4 carbon atoms and mixtures thereof, 0 to 79% mole percent
hydroquinone and an epihalohydrin, said process comprising reacting the
hydroquinone compounds with about 0.95 to about 1.05 equivalents of an
epihalohydrin in the presence of about 1.0 to 1.1 equivalents of a base
and of about one to seven parts by weight solvent for said polymer per
part polymer.
2. Process of claim 1 wherein water is present in the amount of about
0.8 to 10 parts by weight water per part polymer.
3. Process of claim 2 wherein said solvent is immisible with water.
4. Process of claim 1 wherein said solvent is selected from
cyclohexanone, 2-butanone, acetophenone, dichloromethane,
γ-butyrolactone, sulfolane, dimethyl sulfoxide, N-methyl-2-pyrrolidone,
N,N-dimethyl formamide and triethyl phosphate.
5. Process of claim 1 wherein said base is selected from sodium
hydroxide, potassium hydroxide, lithium hydroxide, tetraalkylammonium
hydroxides and alkali metal salts of alcohols.
6. Process of claim 1 wherein a phase transfer catalyst is present in
the amount of up to about 10 mole percent of the hydroquinone compound.
7. Process of claim 6 wherein said catalyst is selected from quaternary
ammonium halides, sulfates, acetates, cyclic polyethers and acyclic
polyethers.
8. Process of claim 7 wherein said catalyst is present in the amount of
1 to 5 mole percent of the hydroquinone compound.
9. Process of claim 8 wherein said catalyst is selected from
benzyltrimethylammonium chloride and benzyltriethylammonium chloride.
10. Process of claim 1 wherein the reaction temperature is from about
50° C. to 100° C.
11. Process of claim 1 wherein the reaction temperature is from about
80° C. to 90° C.
12. Process of claim 1 wherein said hydroquinone phenoxy polymer is
modified with up to about 20 mole percent of another aromatic diol.
13. Process of claim 12 wherein said aromatic diol is resorcinol.
14. Process of claim 1 wherein said hydroquinone phenoxy polymer is
modified with up to about 10 mole percent of another aromatic diol.
15. Process of claim 14 wherein said aromatic diol is resorcinol.
16. Linear hydroquinone phenoxy polymer prepared from at least 21%
hydroquinone substituted with one or two substituents selected from
chlorine or an alkyl group containing 1-4 carbon atoms, and mixtures
thereof, 0 to 79% hydroquinone and an epihalohydrin, said polymer being
characterized by an inherent viscosity of about 0.45 to 0.9 as
determined at 25° C. in a 60/40 by volume mixture of
phenol/tetrachloroethane solvent at a concentration of 0.5
gram/deciliter, a molecular weight distribution, as determined by gel
permeation chromatography, of Mw[]/.sbsb.Mn ≤ about 4 and Mz[]/.sbsb.Mn
≤ about 10.
17. Linear hydroquinone phenoxy polymer of claim 16, wherein the
inherent viscosity is about 0.5 to 0.7.
18. Linear hydroquinone phenoxy polymer of claim 16 wherein
Mw[]/.sbsb.Mn is ≤ about 3.
19. Linear hydroquinone phenoxy polymer of claim 16 modified with up to
about 20 mole percent of an aromatic diol.
20. Linear hydroquinone phenoxy polymer of claim 19 wherein said
aromatic diol is resorcinol.
21. Linear hydroquinone phenoxy polymer of claim 16 modified with up to
about 10 mole percent of an aromatic diol.
22. Linear hydroquinone phenoxy polymer wherein said aromatic diol is
resorcinol.
23. Shaped object of the polymer of claim 16.
24. Shaped object of the polymer of claim 19.
25. Shaped object of the polymer of claim 20.
26. Shaped object of the polymer of claim 21.
27. Shaped object of the polymer of claim 22.
DESCRIPTION:
DESCRIPTION
1. Technical Field
This invention relates to new high molecular weight, essentially linear
hydroquinone phenoxy polymers. It is particularly concerned with
polymers made from substituted hydroquinone, which may be replaced with
up to less than 80 mole percent of another aromatic diol such as
hydroquinone and an epihalohydrin. The polymers are characterized by
low permeability to oxygen and carbon dioxide and are particularly
useful as a gas-barrier layer in multilayer plastic film and in
beverage bottles.
This invention also relates to a new process for producing the novel
hydroquinone polymers, the process involving reacting substituted
hydroquinone, which may be replaced with up to less than 80 mole
percent of hydroquinone with about 0.95 to 1.05 equivalents of an
epihalohydrin in the presence of about 1.0 to 1.1 equivalents of a base
and about 1 to 7 parts by weight of a solvent for the polymer per part
polymer. It is preferred that water be present in the amount of from
about 0.8 to 10 parts by weight polymer and that a phase transfer
catalyst be used.
The new process results in polymer that is essentially free from chain
branches or cross-links which lead to gel particles in the polymer. The
polymer produced by our process is particularly useful for forming
films which exhibit unusual gas barrier properties and thus are
particularly suitable in food-package and beverage bottle applications.
2. Background Art
Two processes for the preparation of hydroquinone phenoxy resin have
been disclosed by A. S. Carpenter, E. R. Wallsgrove and F. Reeder
(British Pat. No. 652,024). In the first process, hydroquinone
bis(glycidyl ether) is allowed to react with hydroquinone under the
influence of a suitable catalyst. We have found that this process gives
material which is highly branched, and in some cases a cross-linked,
infusible resin is obtained.
According to the second procedure of Carpenter et al., hydroquinone
phenoxy resin is formed directly from hydroquinone, epichlorohydrin,
and base (e.g., sodium hydroxide) in an ethanol-water reaction medium.
Low molecular weight polymer precipitates early in the reaction, and
its molecular weight increases slowly thereafter in a heterogeneous
reaction. We have found that this reaction gives erratic results
because of solvent-induced crystallization of the polymer phase. In
some cases, gelled material is produced, while in other cases only low
molecular weight polymer is obtained.
On the other hand, an analogous phenoxy resin, prepared from bisphenol
A (4,4'-isopropylidenediphenol), may be prepared by several methods
similar to the above, but which fail when applied to hydroquinone
phenoxy resin.
These methods fail with hydroquinone phenoxy resin because, being
heterogeneous reactions, they depend upon facile transfer of monomer
molecules from the solution phase to the semi-solid polymer phase.
Hydroquinone phenoxy resin, however, becomes crystalline under the
influence of the water or water/alcohol reaction medium and is no
longer penetrable by monomer molecules. This results in low average
molecular weight, broad molecular weight distribution, and in
irreproducible results. The reaction conditions are suitable for
bisphenol A phenoxy resin, on the other hand, because this latter resin
is not crystallizable under the reaction conditions and remains
permeable to monomer molecules.
Bisphenol A phenoxy resin may be prepared directly from bisphenol A,
base, and epichlorohydrin in an alcohol-water reaction mixture (U.S.
Pat. No. 3,305,528) in a process very similar to the hydroquinone
phenoxy resin process disclosed in British Pat. No. 652,024 above. It
may also be prepared in an "interfacial" process in which one phase of
the reaction medium is aqueous base (e.g., NaOH) and the other phase is
the polymer itself (U.S. Pat. No. 3,767,618). These methods work for
bisphenol A phenoxy resin because it does not crystallize under the
reaction conditions. Because hydroquinone phenoxy resin does
crystallize, it cannot be prepared by these methods.
U.S. Pat. No. 3,238,087 discloses laminated structures in which one
component is a hydroquinone phenoxy resin. However, no process is given
or suggested which will produce the particular hydroquinone phenoxy
polymer disclosed in this specification.
We are not aware of a patent covering the use of a two-phase solvent
system in which the polymer is soluble in one component. Indeed, U.S.
Pat. No. 3,767,618 teaches that such a system leads to inferior results
with the bisphenol A resin (cf. their example 4).
DISCLOSURE OF THE INVENTION
This invention relates to a process for the preparation of
thermoplastic polymers. Specifically, it relates to a process for the
preparation of a substantially linear, high molecular weight phenoxy
resin from hydroquinone substituted, optionally less than 80 mole
percent of hydroquinone epichlorohydrin (or another epihalohydrin) and
a base, such as sodium hydroxide, and the polymer produced thereby.
In our U.S. application Ser. No. 108,722 filed Dec. 31, 1979, now U.S.
Pat. No. 4,267,301, we disclosed hydroquinone phenoxy resins or
polymers in which the aromatic diol component was at least 80 mole
percent of hydroquinone with the remainder being another aromatic diol.
We have found that certain aromatic diols substituted with one or two
substituents which may be chlorine or an alkyl group containing 1-4
carbon atoms used as greater than 20 mole percent of the aromatic diol
component of the polymer result in improved properties over those of
the hydroquinone phenoxy resins disclosed and claimed in our earlier
application. In particular the use of substituted hydroquinone
derivatives such as chloro or dichlorohydroquinone give improved gas
barrier properties and methyl hydroquinone may be used to provide a
polymer with modified crystalline properties or solubility.
The process provides sufficiently mild polymerization conditions to
reduce the degradation of base-sensitive aromatic diols substituted
with one or two substituents which may be chlorine or an alkyl group
containing 1-4 carbon atoms while at the same time remaining
sufficiently vigorous to overcome the steric hindrance to
polymerization presented by even relatively bulky substituents, such as
methyl or tert-butyl groups. The process is applicable to mixtures of
substituted and unsubstiuted hydroquinones in any proportion.
The hydroquinone phenoxy resins or polymers of this invention are
characterized by low permeability to oxygen and carbon dioxide and are,
therefore, useful as a gas-barrier layer in multilayer plastic film
constructions used in food packaging applications and beverage bottle
applications, for example. For use in such applications, the resin is
generally in the form of a thin, uniform film prepared by extrusion,
casting, or other such method. It is highly desirable that polymers
used in this manner be as free as possible from chain branches or
crosslinks, as these lead to the formation of gel particles which cause
imperfections in the polymer film. These imperfections, in turn,
detract from the appearance of the film. Moreover, as is well known,
increasing the amount of chain branching in a polymer results in an
undesirable reduction of flexibility and toughness.
In the food packaging and beverage bottling industries, plastic film
which can be shaped into containers by extrusion blow molding, forging,
stretch blow molding or other processes is highly desirable. These
plastic containers must not only be strong but must also have low
permeability to gases, especially oxygen and/or carbon dioxide, in
order to prevent spoilage of the contents of the package. In order to
provide the optimum combination of properties in the most economical
way, multiple-layer film structures may be produced by lamination,
coextrusion, solution casting or other such methods in which the layers
may consist of different polymers or polymer blends chosen to impart
specific desirable properties to the overall layered film.
It is necessary that such a film have a low permeability to oxygen
and/or carbon dioxide. It is also necessary that the layers of the film
adhere to one another well, preferably when coextruded. The multilayer
film and its individual components should also possess good thermal
stability for ease of melt processing. And to enable the reuse of scrap
laminated film by regrinding and blending of scrap with virgin
material, it is desirable that all of the components of the multilayer
film be compatible when re-extruded. Finally the multilayer film must
be capable of being formed into suitable containers by processes such
as stretch blow molding, forging, and so on, without loss of its
desirable properties.
It is known that poly(ethylene terephthalate) modified with up to about
35 mole percent of other diacids or glycols is particularly well suited
to film extrusion and subsequent thermoforming processes, although its
permeability to oxygen and carbon dioxide is high. We have found that
the substituted hydroquinone phenoxy resins of this invention may be
combined with these polyesters in a multilayer film structure which,
surprisingly, has excellent adhesion between layers when co-extruded,
has good compatibility when scrap is re-extruded, has low gas
permeability and which may be thermoformed without loss of these
desirable properties.
Multilayer constructions may be prepared by various techniques such as
lamination, solvent casting or co-extrusion, the latter being the
preferred process from an economic and practical standpoint. In
addition to flat sheet, the multilayer structure may be in the form of
a tube or may be formed as part of an extrusion blow molding process.
The individual layers of the structure may be composed of pure
components, e.g., polyester or substituted hydroquinone phenoxy resin,
or of a blend of one or more polyesters and substituted hydroquinone
phenoxy resin, such as may be produced by the blending of virgin
polymer with reground scrap multilayer film prior to extrusion. In
general it is preferred that the multilayer structure contain at least
one layer of pure substituted hydroquinone phenoxy resin to obtain the
optimum gas barrier property for the film structure; however, the
desirable mechanical properties of the polyester are essentially
unaffected by blending with substituted hydroquinone phenoxy resin.
We have found that high molecular weight, essentially linear
substituted hydroquinone phenoxy resin may be prepared by the reaction
of a greater than 20 mole percent hydroquinone substituted with one or
two substituents from the group of chlorine or an alkyl group
containing 1-4 carbon atoms, an epihalohydrin such as epichlorohydrin,
and a base such as sodium hydroxide, in a reaction medium consisting of
water and a polymer solvent, such as cyclohexanone. A phase-transfer
catalyst such as benzyltriethylammonium chloride is used to enhance the
transport of reagents across the aqueous/organic phase boundary and
thereby accelerate the reaction rate.
In contrast to the previously-described methods, this phase-transfer
solution polymerization is reproducible, suitable for scale-up, and
gives a product whose ratio of weight-average molecular weight (Mw) to
number-average molecular weight (Mn) is lower (for a given polymer
inherent viscosity) than that obtained with other known methods,
indicating a lower degree of chain branching.
It is surprising that high molecular weight substituted hydroquinone
phenoxy resin can be made in the presence of an organic polymer solvent
in view of the results obtained by T. J. Hairston and W. L. Bressler
(U.S. Pat. No. 3,767,618) who demonstrated that for bisphenol A phenoxy
resin, lower molecular weights are obtained when an organic solvent is
added to the aqueous reaction mixture. Thus, substituted hydroquinone
phenoxy resin behaves in a manner opposite to that of the closely
analogous bisphenol A phenoxy resin.
Broadly the process of our invention for making our novel polymers
comprises a process for the preparation of high molecular weight linear
substituted hydroquinone phenoxy polymer from greater than 20 mole
percent of a hydroquinone substituted with one or two substituents of
the group chlorine and an alkyl group containing 1-4 carbon atoms, and
an epihalohydrin, said process comprising reacting the hydroquinone
compounds with about 0.95 to about 1.05 equivalents of an epihalohydrin
in the presence of about 1.0 to 1.1 equivalents of a base and about 1
to 7 parts by weight solvent for said polymer per part polymer.
A preferred process of this invention involves reacting
chlorohydroquinone with epichlorohydrin in the presence of sodium
hydroxide, in a reaction medium consisting of water, cyclohexanone and
benzyltriethylammonium chloride as the phase-transfer catalyst at a
temperature of about 50° C. to about 100° C. for a time of about 2 to
about 6 hours. At the end of this time, the polymer may be isolated by
any one of several procedures well known to the art.
The novel linear substituted hydroquinone phenoxy polymer of this
invention which may be prepared from greater than 20 mole percent
hydroquinone substituted with one or two substituents of the group
chlorine and an alkyl group containing 1-4 carbon atoms and an
epihalohydrin is characterized by an inherent viscosity of about 0.45
to 0.9 as determined at 25° C. in a 60/40 by volume mixture of
phenol/tetrachloroethene at a concentration of 0.5 gram/deciliter, a
molecular weight distribution, as determined by gel permeation
chromatography, of Mw[]/.sbsb.Mn ≤ about 4 and Mz[]/.sbsb.Mn ≤ 10. The
preferred inherent viscosity is about 0.5 to 0.7 and the preferred
Mw[]/.sbsb.Mn is ≤ 3. Shaped objects such as films made from the
polymer of our invention are particularly useful in a barrier layer in
films and containers for food packaging applications.
The reactants include hydroquinone substituted with one or two
substituents of the group chlorine and an alkyl group containing 1-4
carbon atoms, an epihalohydrin, and a base which is capable of
effecting deprotonation of the aromatic diol and of catalyzing the
polymerization. The substituted hydroquinone may be replaced with up to
less than 80 mole percent of hydroquinone. Also the substituted
hydroquinone may be replaced with up to about 20 mole percent of
bisphenol A, tetrachlorobisphanol A, or phenolphthalein. Compounds in
which the hydroxyl groups are located on adjacent carbon atoms of the
same aromatic ring such as catechol, however, are not preferred because
of the possibility of forming a closed-ring structure with one molecule
of the epihalohydrin component.
Epihalohydrins which may be used include epichlorohydrin,
epibromohydrin and epiiodohydrin, the preferred component being
epichlorohydrin for economic reasons. In addition, 1,3-dihalohydrins,
e.g., glycerol α,γ-dichlorhydrin, may be used if an additional
equivalent of base is used, per equivalent of dihalohydrin, in order to
generate the epihalohydrin in situ.
The base used may be any base strong enough to deprotonate the aromatic
diol to form its mono-anion. Examples of such bases are sodium
hydroxide, potassium hydroxide, lithium hydroxide, tetraalkylammonium
hydroxides, or the alkali metal salts of alcohols such as methanol,
ethanol, or tert-butaneol. Sodium hydroxide is generally the preferred
reagent because of its low cost.
The proportions of reactants used are about 0.95 mole to about 1.05
mole of epihalohydrin per equivalent of diol (or diol mixture) and
about 1.0 to about 1.1 mole of base per mole of diol (or diol mixture).
It is preferred to use about 0.98 mole of epihalohydrin per mole of
diol in order to minimize chain branching; it is also preferred to use
about 1.1 mole of base per mole of diol to provide a convenient
reaction rate while limiting the extent of side reactions.
The solvent system consists of water and an organic solvent which is
capable of dissolving the polymer and may or may not be immiscible with
water. Such solvents include, but are not limited to, cyclohexanone,
2-butanone, acetophenone, dichloromethane, γ-butyrolactone, sulfoane,
dimethyl sulfoxide, N-methyl-2-pyrrolidine, N,N-dimethyl formamide and
triethyl phosphate. The choice of a solvent depends to some extent on
the solubility characteristics of the polymer being prepared; for
chlorohydroquinone phenoxy resin, the preferred solvent is
cyclohexanone.
The proportion of water may range from about 0.8 part by weight water
per part polymer to about 10 parts water per part polymer. The amount
of organic solvent may vary from about 1 part to about 7 parts by
weight solvent per part polymer. It is preferred to use the minimum
amounts of water and organic solvents consistent with convenient
handling in order to enhance the reaction rate. Moreover, it may be
desirable to dilute the organic phase with additional organic solvent
at the end of the reaction in order to facilitate the subsequent
handling of the polymer solution.
The phase-transfer catalyst may be any one of several known to the art,
including quaternary ammonium halides such as methyl
tricaprylylammonium chloride, benzyltriethylammonium chloride,
tetrabutylammonium bromide, etc., cyclic polyethers such as cyclic
hexamer of ethylene glycol; or acyclic polyethers, such as
poly(ethylene glycol). The amount of the catalyst may vary from about
0.01 to 0.10 mole catalyst per mole of diol. Higher amounts may be
used, but are uneconomical. The preferred range is 0.02 to 0.05 mole
catalyst per mole of diol; the preferred catalyst is
benzyltrimethylammonium chloride or benzyltriethylammonium chloride.
The temperature of the reaction may be from about 50° C. to about 100°
C., the preferred range being from about 80° C. to about 90° C. Time of
reaction may be from about 2 to about 6 hours depending upon the
temperature and degree of conversion required. A typical reaction time
is 4 hours at 90° C.
At the end of the reaction, the reaction mixture is acidified by the
addition of acetic acid, phosphoric acid, hydrochloric acid, etc., and
the aqueous phase is drawn off. If desired, the polymer solution may be
diluted, washed with water to remove residual sodium chloride, and the
polymer may be recovered by removal of solvent by means of heat and/or
vacuum. Alternatively, the polymer may be recovered by coagulation of
the polymer solution with a polymer nonsolvent, a procedure which is
well known.
This invention will be further illustrated by the following examples
although it will be understood that these examples are included merely
for purposes of illustration and are not intended to limit the scope of
the invention.
Inherent viscosities (I.V.) were determined in a 60/40 (v./v.) mixture
of phenol and tetrachloroethane at a concentration of 0.5 g./dl., at
25° C.
Determination of molecular weight distribution was performed by gel
permeation chromatography (GPC) on a Waters Associates Model 200 GPC
unit equipped with Styragel columns (Waters Associates), in m-cresol
solvent, at a column temperature of 100° C. The columns were calibrated
with polyethylene terephthalate (PET) standards, and the values of
number-average, weight-average, and z-average molecular weights (Mn, Mw
and Mz) were calculated as PET-equivalent weights. An example of the
calculation is given by N. C. Billingham in "Practical High Performance
Liquid Chromatography," C. F. Simpson, ed., Heyden and Son Ltd., 1978,
page 104, incorporated herein by reference.
EXAMPLE 1
A one-liter resin kettle is charged with 126.81 g. of
chlorohydroquinone, 8.25 g of benzyltrimethylammonium chloride, 200 ml.
cyclohexanone, and 230 ml. water. The kettle is purged with nitrogen
and 82.31 g. of epichlorohydrin and 77.62 g. of 50% aqueous sodium
hydroxide solution are added. The kettle is stirred at 80° C. for 5
hours and heated to reflux for 2.5 hours. The reaction mixture is
acidified with 30 ml. acetic acid, the aqueous layer is drawn off, and
the polymer solution is washed several times with hot water. Removal of
solvent under vacuum yields 161 g. of polymer, PET-equivalent I.V.=0.62
(calculated from GPC data), Mw[]/.sbsb.Mn =2.4
EXAMPLE 2
A 500-ml. Morton flask is charged with 45.47 g.
2.5-dichlorohydroquinone, 2.38 g. benzyltrimethylammonium chloride, 40
ml. cyclohexanone, and 65 ml. water. The flask is thoroughly purged
with nitrogen and 23.15 g. epichlorohydrin and 22.17 g. of a 50%
aqueous solution of sodium hydroxide are added. The reaction mixture is
stirred vigorously at 80° C. for 5 hours, and additional 20 ml.
portions of cyclohexanone are added as necessary to maintain good
stirring (total amount=100 ml.). The mixture is heated under gentle
reflux for 2.5 hours, acidified with acetic acid, and the aqueous layer
is drawn off. The polymer is precipitated by the addition of methanol.
Yield 55 g. PET-equivalent I.V.=0.52 (calculated from GPC data),
Mw[]/.sbsb.Mn =2.6
EXAMPLE 3
The procedure of Example 2 is followed, except that the
dichlorohydroquinone is replaced with 31.22 g. methylhydroquinone.
After heating at 80° C. for 4 hours, the reaction mixture is heated to
reflex for 10 hours before acidification. The polymer is isolated by
removal of solvent under vacuum to yield 39 g. polymer, I.V.=0.45,
Mw[]/.sbsb.Mn =2.4.
EXAMPLE 4--Comparative
Following the method taught in U.S. Pat. No. 2,602,075, a 500 ml. flask
is charged with 28.9 g. (0.20 mole) chlorohydroquinone and 64 ml.
ethanol. The solution is thoroughly purged with nitrogen and a solution
of 8.6 g. (0.21 mole) sodium hydroxide in 25 ml. water is added,
followed by 30 ml. water and 44 ml. ethanol. The solution is heated to
reflux and 18.5 g. (0.20 mole) epichlorohydrin are added slowly. A
precipitate of low molecular weight polymer forms within 10 minutes and
coagulates into a soft plastic mass within 3.5 hours. The ethanol/water
reaction mixture is concentrated by distillation from the reaction, and
in an effort to drive the reaction to completion, 100 ml. of dimethyl
sulfoxide are added to dissolve the mass. The polymer solution is
stirred at 100° C. for 1 to 2 hours without further increase in
solution viscosity. Isolation of the product by precipitation in water
gave a brownish polymer, I.V.=0.34 in phenol/tetrachloroethane solvent.
Two repetitions of the above procedure gave polymers with I.V.'s of
0.33 and 0.36 respectively; the latter polymer also contained insoluble
gels.
EXAMPLE 5--Comparative
Following the general method of U.S. Pat. No. 3,305,582, a 500 ml.
baffled flask is charged with 22.8 g. (0.20 mole) hydroquinone, 7.5 g.
(0.05 mole) chlorohydroquinone, 49 ml. isopropanol, 28 ml. water, and
23.5 ml. (0.25 mole) epichlorohydrin. After degassing 22.35 g. of a 50%
aqueous solution of sodium hydroxide (0.28 mole) is added, followed by
a solution of 3.67 g. benzyltriethylammonium chloride in 15 ml. of 55%
aqueous isopropanol. The mixture is stirred for 16 hours at room
temperature, during which time a fine voluminous precipitate forms. The
mixture is heated to 80° C. for 3.5 hours with stirring, and two 15 ml.
portions of cyclohexanone are added at intervals to maintain good
stirring. After 3.5 hours, 2.3 g. phenol dissolved in 15 ml.
cyclohexanone, followed by 30 ml. cyclohexanone, are added and the
mixture is stirred a further 3.5 hours. The polymeric product obtained
is gelled.
The invention has been described in detail with particular reference to
preferred embodiments thereof, but it will be understood that
variations and modifications can be effected within the spirit and
scope of the invention.